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Cyclic‐Protected Hexafluoroacetone as an Air‐Stable Liquid Reagent for Trifluoromethylations
Author(s) -
Negishi Kazuyuki,
Aikawa Kohsuke,
Mikami Koichi
Publication year - 2016
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201600711
Subject(s) - reagent , chemistry , hexafluoroacetone , trifluoromethylation , aryl , yield (engineering) , trifluoromethyl , intramolecular force , combinatorial chemistry , organic chemistry , medicinal chemistry , alkyl , materials science , metallurgy
An air‐stable liquid trifluoromethylating reagent is readily synthesized from gaseous hexafluoroacetone and 2‐methylproline on a gram scale. The reaction of the trifluoromethylating reagent with tert ‐butoxy cuprate K[Cu(O t Bu) 2 ] leads to the CuCF 3 in high yield. This species is directly formed from the tetrahedral cuprate intermediate through intramolecular migration of the trifluoromethyl group to copper. The CuCF 3 reagent prepared in situ by our method can be used for the trifluoromethylation of aryl iodides, arylboronic acids, and terminal alkynes in good to excellent yields, even on a gram scale. Furthermore, the CuC 2 F 5 reagent can be prepared in the same way, and this can be used in the pentafluoroethylation of arylboronic acids or aryl bromides in good to excellent yields.